The invention is an improvement upon a control device for shutting off a Diesel engine having a reversal valve, a valve which has both supply and shutoff states. A control device of this kind is already known from German Pat. No. 941,236. In the known shutoff device, in order to shut off the engine the supply pump can be reversed by means of a reversal valve, so that the suction chamber of the injection pump is made to communicate with the intake side of the supply pump, while the compression side of the supply pump is made to communicate with the tank. During such reversal, fuel is abruptly withdrawn from the suction chamber of the injection pump, so that the injection pump can no longer supply fuel, and the engine associated with it shuts down. In this known control device the suction action of the known supply pump generates insufficient vacuum in the suction chamber of the injection pump to effect shutoff; thus, the section action of the injection pump itself, because of the extremely precisely manufactured pump elements, is greater than that of the supply pump. Accordingly, even through the reversal valve assumes a "stop" position, the injection pump can continue to aspirate fuel, counter to the intake direction of the supply pump, at least out of the fuel filter but also through the closed valves of the supply pump. When a geared pump is used, as is the case in the patent cited above, the gear-train sealing provided at the gears, which simultaneously act as valves, is not so great that they are impervious to a vacuum. Alternatively, it is flat seat valves which are most frequently used in supply pumps mounted on Diesel injection pumps; and flat seat valves do not attain the sealing and suction effect which is required for shutting off the engine.